Suspension assembly for a heavy vehicle, in particular for a tracked vehicle

Abstract

The invention relates to an oscillating arm suspension assembly for a heavy vehicle, in particular for a track vehicle. According to the invention, the oscillating arm comprises a housing receiving firstly a shock absorber of the type in which a semi-solid elastomer is hydrostatically compressed, said shock absorber being mounted coaxially about the oscillation axis of said arm, and secondly an oleo-pneumatic spring of the two-chamber type, having a hydraulic chamber closed by a sliding piston with a piston rod hinged thereto whose end opposite from the piston is hinged to a fixed member inside said housing.

We claim: 
     
       1. A suspension assembly for a heavy vehicle, the assembly comprising an arm mounted to oscillate on a fixed structure secured to the chassis of the vehicle, and fitted with an axle for a wheel, said axle being offset relative to the oscillation of the arm and being situated beneath said oscillation axis, wherein the oscillating arm comprises a housing receiving firstly a shock absorber comprising a semi-solid elastomer which is hydrostatically compressed, said shock absorber being mounted coaxially about the oscillation axis of said arm, and secondly an oleo-pneumatic spring of the two-chamber type, having a hydraulic chamber closed by a sliding piston with a piston rod hinged thereto whose end opposite from the piston is hinged to a fixed member inside said housing. 
     
     
       2. A suspension assembly according to claim 1, wherein the shock absorber comprises a stator secured to the fixed structure of the vehicle on which the housing of the oscillating arm is rotatably mounted, and in the stator surrounds a rotor which is constrained by a lateral closure plate to rotate with the housing, the fixed member on which the piston rod is fixed being a fork that is mounted directly on said stator. 
     
     
       3. A suspension assembly according to claim 2, wherein the lateral closure plate is fixed via its periphery to the housing, and has a cylindrical extension extending coaxially inside the rotor, said extension and said rotor being coupled to rotate together by means of respective sets of fluting. 
     
     
       4. A suspension assembly according to claim 1, wherein the housing of the oscillating arm includes two cylindrical wells associated with the oleo-pneumatic spring, said wells being adjacent and communicating with each other via a hydraulic connection channel, a first one of the wells having the piston associated with the piston rod sliding therein, and a second one of the wells having a separator piston sliding therein and associated with a chamber containing gas under high pressure. 
     
     
       5. A suspension assembly according to claim 4, wherein the axis of the first well is substantially vertical when the oleo-pneumatic spring is relaxed. 
     
     
       6. A suspension assembly according to claim 4, wherein the piston rod is substantially vertical when the oleo-pneumatic spring is relaxed. 
     
     
       7. A suspension assembly according to claim 4, wherein the two cylindrical wells are disposed on opposite sides of the wheel axle, in order to obtain maximum compactness of the oscillating arm. 
     
     
       8. A suspension assembly according to claim 4, wherein the high pressure gas chamber of the second well is disposed in a lower portion thereof, being delimited by a removable bottom of said well and by the separator piston, said separator piston delimiting an upper chamber containing a volume of hydraulic fluid in direct communication with the hydraulic chamber of the first well, said volume defining a low pressure gas chamber. 
     
     
       9. A suspension assembly according to claim 8, wherein the pressure of the high pressure gas chamber of the second well is selected to be such that the separator piston remains pressed against an associated abutment in a static position and for any vertical force that is less than 1.5 times the vertical force in the static position. 
     
     
       10. A suspension assembly according to claim 9, wherein the chambers of the oleo-pneumatic spring are dimensioned in such a manner that the compression stroke corresponding to compression forces lying in the range 1 to 1.5 times the static force varies little in comparison with variations in vertical forces.